Over the past few years, firefighters have been using various types of systems to ensure their safety while working alone in dangerous situations. For example, firefighters have used a personal alert safety system which is activated manually and has a "panic button" type of switch capable of activating an electronic whistle. Further, the personal alert safety system can sense when its wearer has not moved for a period of time, such as thirty (30) seconds, thereby causing the system's alarm to automatically activate. However, a common problem with these types of personal alert safety systems is that the firefighter frequently forgets to turn them on. That is, in the hustle of jumping off the firetruck, donning gear, assessing the fire situation and taking orders, firefighters will often run into the fire and neglect to activate the safety system.
Firefighters have also utilized temperature alarms which activate an audible alarm whenever the air temperature rises above a preset limit. Due to the efficient insulation of the firefighter garments, firefighters have little feeling for the temperature of the air around them. The heat may actually accumulate in the garment and finally "break through" with no advance warning to the firefighter. Firefighters have also utilized pressure gauges for indicating the pressure within their air cylinders. However, simply providing the air pressure does not communicate to the firefighter the firefighter's remaining air time based upon his or her activity.
As such, prior systems for utilization by firefighters in dangerous firefighting circumstances have numerous limitations.